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Re: [Qemu-devel] [PATCH 0/8] Improve TCG optimizer
From: |
Aurelien Jarno |
Subject: |
Re: [Qemu-devel] [PATCH 0/8] Improve TCG optimizer |
Date: |
Fri, 7 Sep 2012 15:00:53 +0200 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Fri, Sep 07, 2012 at 01:34:10PM +0100, Peter Maydell wrote:
> On 6 September 2012 16:00, Aurelien Jarno <address@hidden> wrote:
> > This patch series improves the TCG optimizer, based on patterns found
> > while executing various guest. The brcond ad setcond constant folding
> > are useful especially useful when they are used to avoid some argument
> > values (e.g. division by 0), and thus can be optimized when this argument
> > is a constant.
> >
> > This bring around 0.5% improvement on openssl like benchmarks.
>
> This didn't overall seem to make much difference on my popular
> embedded benchmark setup. However I am rapidly losing confidence
> in the benchmark since from run to run individual tests can have
> results which vary by a factor of two, which is such high
> variation it's almost impossible to say whether a change has
> had an overall +1% or -1% effect. Hohum.
>
I am usually doing the tests by setting the CPU performance to
performance and by pinning QEMU to a given CPU, on a machine without or
with very few other tasks. This improve the stability of the results.
Unfortunately it's not easy to do that on a laptop, especially when
running on battery.
--
Aurelien Jarno GPG: 1024D/F1BCDB73
address@hidden http://www.aurel32.net
- [Qemu-devel] [PATCH 8/8] tcg/optimize: add constant folding for brcond, (continued)
- [Qemu-devel] [PATCH 8/8] tcg/optimize: add constant folding for brcond, Aurelien Jarno, 2012/09/06
- [Qemu-devel] [PATCH 6/8] tcg/optimize: swap brcond/setcond arguments when possible, Aurelien Jarno, 2012/09/06
- [Qemu-devel] [PATCH 7/8] tcg/optimize: add constant folding for setcond, Aurelien Jarno, 2012/09/06
- [Qemu-devel] [PATCH 5/8] tcg/optimize: simplify shift/rot r, 0, a => movi r, 0 cases, Aurelien Jarno, 2012/09/06
- [Qemu-devel] [PATCH 3/8] tcg/optimize: simplify or/xor r, a, 0 cases, Aurelien Jarno, 2012/09/06
- Re: [Qemu-devel] [PATCH 0/8] Improve TCG optimizer, Richard Henderson, 2012/09/06
- Re: [Qemu-devel] [PATCH 0/8] Improve TCG optimizer, Peter Maydell, 2012/09/07
- Re: [Qemu-devel] [PATCH 0/8] Improve TCG optimizer,
Aurelien Jarno <=